This invention relates to electric motor driven centrifugal fluid pumps and particularly to pumps of the sort that have no rotating axle or bearings that penetrate a wall of the pump housing and so the housing is completely sealed against any leakage of the fluid that is pumped and used to pump cooling oil in the cooling system of the electron beam tube of an X-Ray system.
Heretofore, magnetically driven centrifugal pumps that are completely sealed up and have no drive shaft or bearing opening through any wall of the housing of the pump have been provided for sealed cooling systems. Such pumps are often specified where, for any number of reasons, no fluid leakage from the pump can be. For example: the fluid may be very contaminating; or it may be poisonous or radioactive; or it may simply be a cooling fluid in a closed system that cannot tolerate any leaks.
An improved electric motor driven centrifugal fluid pump for this use has a sealed housing that contains the fluid, the motor and the pump is described in U.S. Pat. No. 5,890,880, issued Apr. 6, 1999, entitled xe2x80x9cSealed Motor Driven Centrifugal Pumpxe2x80x9d, to Ferdinand Lustwerk, the inventor herein.
The pump described in U.S. Pat. No. 5,890,880 has the advantage that the motor is cooled by the pumped fluid by compelling the fluid to flow through parts of the motor and carry heat therefrom so that the motor can be operated at higher power without overheating.
It is an object of the present invention to provide such a fluid pump and electric drive motor in an assembly contained within a sealed housing as the electron beam tube cooling system of an X-Ray system, wherein a heat exchanger for cooling the pumped fluid is integrated with the assembly in a compact package.
It another object of the present invention to provide such a pump and electric drive motor assembly with a heat exchanger wherein means are provided for compelling some fluid flow around the electric motor in the sealed housing to reduce the static pressure on the pump rotor and so reduce the thrust load on the motor bearings.
According to the present invention, an electric motor driven centrifugal fluid pump includes a pump rotor and a pump drive motor in a sealed X-Ray tube cooling fluid system has a heat exchanger for the cooling fluid integrated therewith in a compact package. In the compact package, a sealed X-Ray tube cooling fluid (primary fluid) annular passage is provided around the motor and a secondary fluid annular passage is provided around the primary fluid annular passage to cool the primary fluid. The pump is then capable of providing the X-Ray tube cooling fluid (primary fluid) in a compact package that includes a heat exchanger without connections and hoses to a separate heat exchanger in the X-Ray system.
These and other objects and features of the present invention will be apparent to those skilled in the art from the following specific description of embodiments of the invention taken in conjunction with the drawings.